Cherry pick previous feature-spotrequest branch

Conflicts:
	cloud_copasi/web_interface/templates/pool/ec2_pool_add.html
	html5up/static/js/pool_launch.js
Tweak pool launch view
Add spot price attributes to EC2Pool ORM
Make spot price bid field required, with defualt of False
South migration schema for previous change
Fix mistake in spot price bid in EC2Pool ORM
Fiddle with migration history, and rename spot request fields
Remove EC2 instance types unable to support spot instances
Rename some attributes of SpotInstance ORM
launch pool now launches spot requests